Field of the Invention
The present invention relates to a rotary valve actuator arrangement for an automobile engine, and more particularly to a throttle valve actuator arrangement useable for variably controlling an amount of intake air induced to the engine depending on an amount of manipulation of an accelerator.
U.S. Pat. No. 5,823,165 discloses an electric-driven throttle valve actuator arrangement. The arrangement includes a casing having an intake air passage, a valve shaft rotatably disposed within the casing, a valve body rotatable with the valve shaft to open and close the intake air passage, an electromagnetic actuator for driving the valve body via the valve shaft, and a pair of springs for biasing the valve body toward the closed position or the intermediate position between the closed position and the full open position. The electromagnetic actuator includes a stator disposed on the casing and a rotor disposed on the valve shaft. The stator includes a stator core and a pair of coils wound on the stator core in opposite directions. The rotor includes a disk fixed to one end of the valve shaft, a permanent magnet fixed to the disk in an opposed relation to the stator core. The stator core, the rotor and the respective coils cooperate to generate opposite magnetic fields acting for moving the valve body toward the full open position and the closed position when the coils are energized, respectively. The rotation of the valve body is restricted at the closed position and the full open position by contact of a stopper piece of a lever attached on the valve shaft with two stoppers projecting from the casing. When one of the coils is activated with a pulse current in a variable duty ratio, the valve shaft can be rotated depending on an opening degree of the valve body corresponding to the duty ratio. The valve body thus rotates with the valve shaft to open and close the induction passage in the casing so that the amount of the intake air can be variably controlled.